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Web app tracks radon in Minnesota counties

A screen capture of Minnesota Department of Health’s new online radon mapping tool shows the percentages of properties in all 87 counties that have tested high for the radioactive gas; darker shades represent higher percentages. (source: MDH Indoor Air Unit data from 2010-2014)

A majority of Minnesota counties have high average levels of radon, according to a new online tool that tracks the prevalence of the odorless gas linked to thousands of lung cancer deaths in the U.S. each year.

The Minnesota Department of Health collected radon data from 86,000 residential and commercial properties tested from 2010-2014, and found 67 of the state’s 87 counties have average radon levels at or greater than 4 pCi/L — the threshold at which the Environmental Protection Agency recommends mitigation measures.

The data and an interactive map showing county radon levels can be found at

Washington County fared comparatively well among east Metro and southeastern Minnesota counties, with nearly 36 percent of 3,796 tested properties in the 4 pCi/L or higher category.

Results from 6,555 tests in neighboring Dakota County found just under 42 percent of properties at or above 4 pCi/L, while nearly 59 percent of 809 tested properties reached that level in Goodhue County.

The highest percentages of properties that tested high for radon are found in the southwest corner of the state, as well as Polk County in the northwest and Wabasha County near Rochester.

The average radon level in Minnesota is 4.6 pCi/L, more than three times the national average of 1.3 pCi/L, according to the health department.

“Radon is a problem all across Minnesota but it can be hard to know if you have a problem because you can’t see it or smell it,” said Dan Tranter, MDH indoor air program supervisor, in a news release. “With the housing market heating up this summer, it is important for home buyers to know their rights and get potential homes tested for radon so any problems can be fixed before buying a house.”

A 2014 state law requires home sellers to inform buyers if the property was tested for radon and what levels were recorded.

The number of Minnesota properties tested for radon increased after 2010 to a high of 30,745 in 2013. Health officials credit the Minnesota Radon Awareness Act, awareness campaigns, outreach partnerships and an improving economy for the increase.

Radon is a naturally occurring radioactive gas that seeps into properties from the soil through cracks in walls or foundations. It is the leading cause of lung cancer nationally among non-smokers, and is linked to 21,000 lung cancers deaths annually, according to the EPA.

Home test kits for radon use charcoal to absorb the gas over several days. Kits are then sealed and mailed to a lab for testing. Experts recommend to test during the winter months when houses are sealed and radon levels are highest.

Radon mitigation options include sealing cracks and openings and installing ventilation or pressurization systems.

For more information on radon and tips for choosing a mitigation contractor, visit the MDH Radon website at

Michael Brun

Michael Brun joined RiverTown Multimedia at the Red Wing Republican Eagle in March 2013, covering county government, health and local events.  He is a graduate of the University of Wisconsin-River Falls journalism program.

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